The comparison you keep doing by hand, and the two numbers it needs

Two things I keep seeing in projects that stall, and they are not technical problems.

The first is a comparison done by hand. Two lists, side by side, checked one item at a time, with the answer thrown away when it is done. The second is a cost nobody wrote down before starting.

They look unrelated. They are the same mistake.

The comparison that lives in a spreadsheet

Somebody has two lists of things — the items in a game, the entries in a table, the pages of a reference — and they need to know what is in one and not in the other.

The obvious move is to paste both into a spreadsheet and use a formula. That works exactly once.

After that, three things break. The spreadsheet becomes a second copy of the data, so every update has to be done twice. Nobody can share the result without sharing the file. And the comparison has no address, so when somebody asks in a comment what the answer was, the answer is gone.

The fix is not a better spreadsheet. It is giving the comparison a URL.

When the comparison is a page, it can be sent, it can be linked, it can be reopened a year later and it still says what it said. That is the whole difference between a tool you used once and a tool that stays.

DexBase is built on that idea: it compares lists, tables and references in one place, and the result is a page rather than a file. That is DexBase, and the site is at https://dexbase.org.

The cost that was never written down

The second failure is the same shape in money. You pick an API model, you ship the feature, and a month later the invoice arrives and it is not what anyone expected.

Usually nobody was careless. The per-token price was known, and it was treated as the cost. It is not the cost. The cost is tokens per request multiplied by requests per day multiplied by days in the month, and any of the three can move without warning.

CostUse prices it before you build: pick a model, paste a sample of real output, and see what the published rate becomes over a realistic month, with the source and the date of the check on the page. The tool is CostUse, and the site is at https://costuse.com.

The rule is the same in both cases. Get the number before you commit, and give the number an address so other people can check it.

Two habits, one idea

What these two problems have in common is that they are both cheap to avoid and expensive to discover late.

Spend twenty minutes making the comparison a URL and the cost a number, and you get two things that survive: a result other people can open, and a figure you can compare against the invoice later. Skip both steps and you get a file nobody can find and a bill nobody can explain.

Neither of those is a large amount of work. It just has to happen before, not after.